Experimental Investigation on the Thermal and Flow Characteristics in the IRWST Under Spraying of the Steam From Automatic Depressurization System in AP1000 Plant

2016 ◽  
Author(s):  
Daogang Lu ◽  
Yuhao Zhang ◽  
Zhongyi Wang ◽  
Guanghao Wu ◽  
Qiong Cao
Keyword(s):  
Thermal Stratification ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Convection Flow ◽  
Water Storage Tank ◽  
Image Velocimetry ◽  
Large Tank ◽  
Coolant System

In AP1000 plant, the automatic depressurization system (ADS) works to discharge the high-temperature and high-pressure steam from the Reactor Coolant System (RCS) primary side to the In-containment Refueling Water Storage Tank (IRWST) in the LOCA conditions. In particular, for the AP1000 plant, both the IRWST and ADS spargers are specially designed, and the ADS spargers are located in one corner of the IRWST. All the factors lead to the special and complicated thermal and flow behavior in the IRWST, which in turn have great influences on the condensation effects of the ejected steam. In the present work, an overall scaled-down IRWST and ADS sparger models are built to study the condensation and mixing phenomena in the accidental depressurization events in AP1000. Thermocouples matrix with more than 200 T-type sheathed thermocouples are utilized to measure the three dimensional temperature in the large tank. The Particle Image Velocimetry (PIV) is employed for the measurement of the natural convection flow velocity. Based on the experimental data, the local spraying flow patterns, flow behavior, and thermal stratification phenomena in IRWST etc. are analyzed. The results indicate that the spraying steam condensation flow patterns are closely related to the subcooling degree in the IRWST. In addition, the stratification number is developed to evaluate the thermal stratification extent in the IRWST, which indicates that only part of the fluid are used efficiently for condensing the spraying steam directly.

scholarly journals Swirling Flows Characteristics in a Cylinder Under Effect of Buoyancy

Mechanika ◽  
2021 ◽  
Vol 27 (3) ◽  
pp. 201-208
Author(s):  
Mustafa FEKHAR ◽  
Rachid SACI ◽  
Renée GATIGNOL
Keyword(s):  
Aspect Ratio ◽  
Thermal Stratification ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Swirling Flows ◽  
Viscous Effects ◽  
Thermal Buoyancy ◽  
State Diagrams ◽  
The Core ◽  
Flow Stagnation

Thermal buoyancy, induced by injection or by differential heating of a tiny rod is explored to control breakdown in the core of a helical flow driven by the lid rotation of a cylinder. Three main parameters are required to characterize numerically the flow behavior; namely, the rotational Reynolds number Re, the cavity aspect ratio and the Richardson number Ri. Warm injection/rod, Ri > 0, is shown to prevent on-axis flow stagnation while breakdown enhancement is evidenced when Ri < 0. Results revealed that a bubble vortex evolves into a ring type structure which may remain robust, as observed in prior related experiments or, in contrast, disappear over a given range of parameters (Λh, Re, Ri > 0). Besides, the emergence of such a toroidal mode was not found to occur under thermal stratification induced by a differentially heated rod. Moreover, three state diagrams were established which provide detailed flow characteristics under the distinct and combined effects of buoyancy strength, viscous effects and cavity aspect ratio.

PIV Measurements in Diffuser of the Radial Pump

2015 ◽  
Author(s):  
Sung Yong Jung ◽  
Young Uk Min ◽  
Kyung Lok Lee
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Internal Flows ◽  
Piv Measurements ◽  
Image Velocimetry ◽  
Acquisition Device ◽  
Field Information ◽  
Radial Pump

The performance characteristics of the radial pump commonly used as a multistage (8 or 10 stage) pump have been investigated experimentally. Due to the complex three-dimensional geometries, the hydraulic performance of multistage pumps is closely related to the internal flows in diffuser and return vanes. In order to investigate the flow characteristics in these regions by Particle Image Velocimetry (PIV) technique, a transparent pump is designed. A 532 nm continuous laser and a high-speed camera are used as a light source and an image acquisition device, respectively. The velocity field information in a diffuser of the radial pump is successfully obtained by two-dimensional PIV measurements at various operating conditions.

Experimental and Numerical Study of Hydrodynamic Cavitation of Orifice Plates with Multiple Triangular Holes

2012 ◽  
Vol 256-259 ◽  
pp. 2519-2522 ◽  
Author(s):  
Zhi Yong Dong ◽  
Qi Qi Chen ◽  
Yong Gang Yang ◽  
Bin Shi
Keyword(s):  
Velocity Profile ◽  
High Speed ◽  
Numerical Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Orifice Plate ◽  
Hydrodynamic Cavitation ◽  
High Speed Photography ◽  
Hydraulic Characteristics ◽  
Image Velocimetry

Hydraulic characteristics of orifice plates with multiple triangular holes in hydrodynamic cavitation reactor were experimentally investigated by use of three dimensional particle image velocimetry (PIV), high speed photography, electronic multi-pressure scanivalve and pressure data acquisition system, and numerically simulated by CFD software Flow 3D in this paper. Effects of number, arrangement and ratio of holes on hydraulic characteristics of the orifice plates were considered. Effects of arrangement and ratio of holes and flow velocity ahead of plate on cavitation number and velocity profile were compared. Distribution of turbulent kinetic energy and similarity of velocity profile were analyzed. And characteristics of cavitating flow downstream of the orifice plate were photographically observed by high speed camera. Also, a comparison with flow characteristics of orifice plate with hybrid holes (circle, square and triangle) was made.

A High-Order LES Turbulent Model to Study Unsteady Flow Characteristics in a High Pressure Turbine Cascade

2008 ◽  
Author(s):  
Tomohiko Jimbo ◽  
Debasish Biswas ◽  
Yasuyuki Yokono ◽  
Yoshiki Niizeki
Keyword(s):  
Physical Process ◽  
Pressure Loss ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Measured Data ◽  
High Order ◽  
Turbulent Model ◽  
Loss Mechanism

In this work, unsteady viscous flow analysis around turbine blade cascade using a High-Order LES turbulent model is carried out to investigate basic physical process involved in the pressure loss mechanism. This numerical analysis is assessed to the wind tunnel cascade test. Basically, all the physical phenomena occurring in nature are the effect of some cause, and the effect can somehow be measured. However, to understand the cause, detail information regarding the visualization of the phenomena, which are difficult to measure, are necessary. Therefore, in our work, firstly the computed results are compared with the measured data, which are the final outcome of the cause (of the phenomena under investigation), to verify whether our physics-based model could qualitatively predict the measured facts or not. It was found that the present model could well predict measured data. Therefore, the rest of the computed information, which were difficult to measure, were used to visualize the overall flow behavior for acquiring some knowledge of the physical process associated with the pressure loss mechanism. Our study led to an understanding that the interaction of the vortex generated on the suction and pressure surface of the blade and the secondary vortex generated on the end-wall, downstream the trailing edge resulted in the formation of a large vortex structure in this region. This unsteady three-dimensional flow characteristic is expected to play an important role in the pressure loss mechanism.

A Wind Tunnel Study of Heat Transfer Over Complex Terrain

2003 ◽  
Author(s):  
Michelle Pantoya ◽  
Kenneth Shifflett ◽  
Walter Oler ◽  
William Burton
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Wind Energy ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Flow Patterns ◽  
Atmospheric Conditions ◽  
Unstable Flow ◽  
Scaled Model ◽  
Atmospheric Flow

Maximizing wind energy resources requires a detailed understanding of atmospheric flow behavior over complex topography. The objective of this research is to examine unstable flow behavior over a three-dimensional topographic model, representative of mesa terrain that is common in West Texas. The goal is to develop an understanding of how unstable atmospheric conditions caused by surface heating affect boundary layer flow patterns in the natural environment. This objective was accomplished by experimentally monitoring transient thermal behavior of narrow band liquid crystals over a scaled model. Photographic data was collected as the heated model was subjected to a cooler flow field. The transient isotherms result from cooling as the model is exposed to flow in an atmospheric boundary layer wind tunnel. Results suggest that flow patterns associated with unstable conditions can be explained by increased wind speeds on the lee side of a mesa followed by vigorous mixing causing increased cooling rates around the mesa sides. The results could be used to improve the accuracy of numerical atmospheric flow models, assess the feasibility of developing wind turbine sites, and increase the knowledge-base in order to advance wind energy forecasting techniques.

Studies on Unsteady Flow Characteristics in a High Pressure Turbine Cascade Based on a High-Order Large Eddy Simulation Turbulence Model

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Tomohiko Jimbo ◽  
Debasish Biswas ◽  
Yoshiki Niizeki
Keyword(s):  
Turbulence Model ◽  
Physical Process ◽  
Pressure Loss ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Measured Data ◽  
High Order ◽  
Loss Mechanism

In the present paper, unsteady viscous flow analysis around turbine blade cascade using a high-order LES turbulence model is carried out to investigate the basic physical process involved in the pressure loss mechanism. This numerical analysis is assessed to the wind tunnel cascade test. Basically, all the physical phenomena occurring in nature are the effect of some cause, and the effect can somehow be measured. However, to understand the cause, detail information regarding the visualization of the phenomena, which are difficult to measure, are necessary. Therefore, in the present paper, firstly the computed results are compared with the measured data, which are the final outcome of the cause (of the phenomena under investigation), to verify whether our physics-based model could qualitatively predict the measured facts or not. It was found that the present model could well predict measured data. Therefore, the rest of the computed information, which were difficult to measure, were used to visualize the overall flow behavior for acquiring some knowledge of the physical process associated with the pressure loss mechanism. The present study led to an understanding that the interaction of the vortex generated on the suction and pressure surface of the blade and the secondary vortex generated on the end wall, downstream of the trailing edge, resulted in the formation of a large vortex structure in this region. This unsteady three-dimensional flow characteristic is expected to play an important role in the pressure loss mechanism.

scholarly journals Supercritical flow at an abrupt drop: flow patterns and aeration

1998 ◽  
Vol 25 (5) ◽  
pp. 956-966 ◽  
Author(s):  
H Chanson ◽  
L Toombes
Keyword(s):  
Shock Waves ◽  
Open Channel ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Three Dimensional Flow ◽  
Supercritical Flow ◽  
Drop Flow ◽  
Supercritical Flows ◽  
The Impact

Stepped waterways and cascades are common features of storm waterways, at dam outlets, and in water treatment plants. At an abrupt drop, open channel flows are characterized by the presence of shock waves and a substantial flow aeration. There is, however, little information on the basic flow characteristics. The study presents new experimental data obtained in a 0.5-m-wide stepped flume with an unventilated nappe. The investigations describe the three-dimensional flow patterns, including shock waves, standing waves, and spray, downstream of the nappe impact. The characteristics of the flow patterns are similar to those observed with abrupt expansion supercritical flows. Downstream of the drop brink, substantial aeration takes place along the nappe interfaces and the flow downstream of the impact is deaerated.Key words: abrupt drop, supercritical flow, shock waves, flow patterns, cascade.

Physiological Flow Studies in Exact-Replica Atherosclerotic Carotid Bifurcations

2003 ◽  
Author(s):  
J. Bale-Glickman ◽  
K. Selby ◽  
D. Saloner ◽  
O¨. Savas¸
Keyword(s):  
Chaotic Behavior ◽  
Three Dimensional ◽  
Carotid Bifurcation ◽  
Flow Patterns ◽  
Shear Stresses ◽  
Multiple Sources ◽  
Complex Flow ◽  
Physiological Flow ◽  
Image Velocimetry ◽  
Recirculation Zones

Some results from a series of physiological flow experiments in a model of an atherosclerotic carotid bifurcation are presented. The flow model exactly replicates the lumen of the plaque excised intact from a patient with severe carotid atherosclerosis. Flow visualization (FV) and particle image velocimetry (PIV) are employed as the tools for this study. The complex internal geometry of the diseased artery combined with the pulsatile input flows gives rise to complex flow patterns. The flow fields are highly three-dimensional and chaotic with details varying from cycle to cycle. These flow patterns also include internal jets, three-dimensional shear layers, numerous separation/recirculation zones and stagnation lines. The vorticity and streamline maps confirm this complex and three-dimensional nature of the flow. Planar streamline maps show the three-dimensional flow by the multiple sources/sinks throughout the model. Wall shear stresses (WSS) are estimated to range form about −7 Pa to 34 Pa at the stenotic neck over time with the peak at peak systolic. These WSS also exhibit chaotic behavior during pulsatile flow cycles.

scholarly journals 3D gas-liquid interfaces and flow characteristics of two-phase flows in horizontal tubes

2021 ◽  
Vol 2116 (1) ◽  
pp. 012072
Author(s):  
Jingzhi Zhang ◽  
Bengt Sunden ◽  
Vishwas Wadekar ◽  
Zan Wu
Keyword(s):  
Flow Pattern ◽  
Void Fraction ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Industrial Applications ◽  
Liquid Interfaces ◽  
Two Phase Flows ◽  
Two Phase ◽  
Void Fractions

Abstract In order to investigate the characteristics of gas-liquid two-phase flows in horizontal mini circular tubes with inner diameters of 3.14 and 6.68 mm, a prism is adopted to improve the light path in the visualization experimental setup. The front and top views of air-water two-phase flow patterns in two tubes are captured synchronously based on the improved method. Three-dimensional gas-liquid interfaces, flow pattern maps, and void fraction are obtained. The experimental results show that tube diameters have significant effects on flow patterns transition lines in the flow pattern maps, but the void fractions are independent on channel sizes. The effect of gravity gradually decreases with decreasing tube diameter, while that of surface tension is enhanced. As a consequence, the proportion of annular flow in flow pattern map increases in mini tubes, while the reverse is true for the stratified flow whose proportion decreases dramatically in mini channels. The void fraction increases with increasing gas quality. Experimental void fractions obtained using the three-dimensional gas-liquid interfaces fit well with correlations in the open literature. The shape of PDF distributions varies with flow patterns, which could be used to identify flow patterns in industrial applications.

Modeling and Computation of Flow in a Passage With 360-Degree Turning and Multiple Airfoils

1993 ◽  
Vol 115 (1) ◽  
pp. 103-108 ◽  
Author(s):  
W. Shyy ◽  
T. C. Vu
Keyword(s):  
Porous Medium ◽  
Global Analysis ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Hydraulic Turbine ◽  
Complex Flow ◽  
The Individual ◽  
Spiral Casing

The spiral casing of a hydraulic turbine is a complex flow device which contains a passage of 360-degree turning and multiple elements of airfoils (the so-called distributor). A three-dimensional flow analysis has been made to predict the flow behavior inside the casing and distributor. The physical model employs a two-level approach, comprising of (1) a global model that adequately accounts for the geometry of the spiral casing but smears out the details of the distributor, and represents the multiple airfoils by a porous medium treatment, and (2) a local model that performs detailed analysis of flow in the distributor region. The global analysis supplies the inlet flow condition for the individual cascade of distributor airfoils, while the distributor analysis yields the information needed for modeling the characteristics of the porous medium. Comparisons of pressure and velocity profiles between measurement and prediction have been made to assess the validity of the present approach. Flow characteristics in the spiral casing are also discussed.

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